docs: def release_filename(self, id_):
          """Release a file name.
          """
  
          entry = self.__entries.get(id_)
          if entry is None:
              raise ValueError("Invalid filename id (%d)" % id_)
  
          # Decrease reference count and check if the entry has to be removed...
          if entry.dec_ref_count() == 0:
              del self.__entries[id_]
              del self.__id_lut[entry.filename]